1. Field of the Invention
The present invention relates to a measuring instrument for the thermal and/or reactive properties of one or several samples of material. The thermal and/or reactive properties of a material are materialized by a heat flow either entering or leaving the sample under given conditions.
2. Description of the Related Art
The hitherto known devices of such type are most frequently complex, heavy, voluminous instruments that must be exclusively used in laboratories because they cannot be easily moved and whose cost is high. Furthermore, the volume of the measuring chamber of these instruments and the reaction time of the cells used bring about a considerable thermal inertia of these devices, so that a high-quality isothermic chamber must be used. This, however, elevates the costs of these devices and increases their sizes.
Further, from the claims of patent WO 91/02229 is known a measuring cell for the temperature difference between two zones of its surface that is susceptible to be used in a measuring instrument for the thermal properties of a sample of material. A cell of such type, however, is fragile and cannot be used as is without risking that it be damaged because of the handling necessary for the placing and withdrawing of a sample. Furthermore, it must be connected to an electronic control circuit and it must be continue to be possible to tap and disconnect it, in particular, for a change of components or for preventive maintenance operations. This cell may operate in an open atmosphere but the measurements it takes at such time are false because of the perturbations due to the ambient atmosphere.